Jackie Warner: Drink 3 Liters of Water with Lemon

You already know drinking water is good for your overall health, but fitness expert, celebrity trainer, and star of “Personal Training with Jackie: 30 Day Fast Start" Jackie Warner has a tip to take it up a notch in the weight-loss department. She recommends drinking 3 liters of water with lemon each and every day.

"Adding the lemon helps to detoxify the liver and metabolizes fat, so this can speed up metabolism by about 33 percent," Warner says. "That burns about 100 extra calories per day!"

Kathy Smith: Listen to Your Hunger

Even if you can't fully change your diet for the better, one simple way to lose weight is to eat just a little less. And the easiest way to do that is by listening to your hunger. Kathy Smith, creator of the "Ageless with Kathy Smith" DVD line, says to eat slowly, savor every bite, and pay attention to when you begin to feel full—otherwise you can consume more calories than your body needs at each meal.

"When you get the signal that you’ve had enough, sprinkle salt on the rest of your plate to avoid nibbling on the leftovers, " Smith says. "Those little bits of calories can add up quickly over the week."

Jennifer Cohen: Don't Buy Diet Food

Jennifer Cohen, Weight Watchers’ spokeswoman and author of No Gym Required, warns to not just choose foods because they're marketed as "good for weight loss." Instead, choose what foods you're going to eat based on their nutritional value and health benefits. By eating healthy foods that are rich in nutrients, you're sure to lose weight pretty effortlessly.

"Before you plan a shopping trip or order out, look up the nutritional value of the foods you're considering and ask yourself if your list matches up with your needs and goals," Cohen says.

Mandy Ingber: Eat a Salad Every Day

Can losing weight be as simple as eating a salad for lunch every day? Mandy Ingber, the creator of Yogalosophy and celebrity yoga instructor to Jennifer Aniston, Kate Beckinsale, Ricki Lake, Brooke Shields, and Helen Hunt, thinks so.

"Replace your lunchtime meal with a large salad loaded with healthy greens," Ingber says. "If you are a meat-eater, add some lean protein. Load your salad with avocado, nuts, and all sorts of veggies that add color to your meal."

Nicole Nichols: Eat More Regularly

In order to lose weight, you should never let yourself get too hungry, says Nicole Nichols, fitness expert and editor for SparkPeople.com, who was recently named America's "Top Personal Trainer to Watch" by ACE and Life Fitness. In fact, waiting too long between meals can encourage overeating later.

"So plan for one to two snacks a day as needed, and you’ll likely eat less and avoid binges later," Nichols says.

Tara Stiles: Start Juicing

And by juicing, we mean drinking fresh vegetable juice! Tara Stiles, the founder and owner of Strala yoga studio, personal yoga instructor to Deepak Chopra, and author of the best-selling book Slim Calm Sexy Yoga, says that juicing is the best thing she ever did for her health.

"Cucumber, kale, carrot, ginger...it is so good for you, gives you so much energy, and actually tastes good!" Stiles says. "The coolest side effect is that I stopped craving sugar and salts! Just like that, without trying. Amazing!"

Kristin McGee: Keep Almonds on Hand

We all know what it's like to be out on-the-go, totally hungry with no healthy options in sight. That's why Kristin McGee, a celebrity yoga and Pilates instructor whose clients include Tina Fey, Steve Martin, Christine Taylor Stiller, LeAnn Rimes, and Bethenny Frankel, recommends packing an Altoids-sized container of raw almonds with you at all times. A small portion of any raw nut helps to keep your blood sugar stable.

"The perfect portion size of about 22 almonds, 15 cashews, or eight walnut halves will fit in one, and studies have proven that people who eat nuts weigh less and eat less overall," McGee says. "The belly-slimming monounsaturated fats are excellent, and each type of nut has great benefits—walnuts have omega-3s and almonds are high in vitamin E. Plus, a little Altoids tin can fit in a purse pocket anywhere, so there's no excuse!"

Jari Love: Add Psyllium and Flaxseeds to Your Diet

Very rarely do you get advice to add to your diet, but that's exactly what star of the new "Get Extremely Ripped: Revved to the Max" DVD, Jari Love's easy diet secret is. She swears by psyllium seed husks, which are high in belly-filling fiber, and flaxseeds, which are rich in omega-3 fatty acids and antioxidants, for helping her stay at a healthy weight.

"Take your psyllium husks and flaxseeds, put them both into a Ziploc bag, and shake it up," Love says. "Keep this mixture in the fridge and add a tablespoon to each protein shake you drink throughout the day. This will help to keep you regular and give you those extra nutrients you need."

Andrea Metcalf: Eat Protein with Every Meal

Whether it's meat or a vegetarian protein like tofu or beans, Andrea Metcalf, a healthy lifestyle expert and author of Naked Fitness: The Proven 28 Day Weight Loss Program for a Slimmer, Fitter, Pain-Free Body, says that protein at every meal is a must for keeping away those hunger pangs. "Eat protein with each meal to stave off cravings," she says.

Fit Chef Katy Clark: Don't Drink Alcohol Standing Up

Here's a simple rule to follow whenever you're at a party or a happy hour: don't stand and sip! That's the advice of Fit Chef Katy Clark from season 7 of Food Network Star. Calories really add up when you're drinking alcohol, so be extra mindful of each drink, she says.

"I found that I grab a drink because that is the expected party behavior, and I use my drink as a buffer and will just take sips to look busy, even though I'm not really enjoying it," she says. "Instead, I drink cocktails and wine during great sit-down, relaxed moments. And at the party, I stand with bubbly water or nothing in my hand so that I can give out better hugs!"

Linda LaRue: Watch Carb Serving Sizes

While carbohydrates are great for energy, it's easy to eat way too many if you're paying attention. Fitness expert and creator of the total-body core training system The Core Transformer Linda LaRue recommends to keep portions in check—especially when you're eating out.

"Remember that a recommended carbohydrate serving—such as pasta, pizza, bread, or rice—is 1/3 to 1/2 cup. That's the size of a golf ball or mouse," she says. "Most restaurants give you three cups of pasta. That's the equivalent of six carb servings!"

John Dull and Michele Collier: Choose Greek Yogurt

Everyone thinks of yogurt as a pretty healthy snack choice, but all yogurts are not created equal, say the creators of the "Supreme 90 Day" system John Dull and Michele Collier. In fact, many yogurts—including low-fat varieties—are loaded with sugar.

"A better choice is Greek-style yogurt," they say. "They have more protein per serving and very little sugar. Try adding fresh fruit for an added treat!"

Dr. Lynn: Swap Spicy Mustard for Mayo

Swapping mustard for mayo is a no-brainer. But using spicy mustard is even better, says Dr. Lynn Anderson. This is because hot spicy mustard amps up the metabolism by creating a heat effect in the body, she says.

"To increase metabolism and curb appetite, drink a glass of water mixed with a tablespoon of hot spicy mustard just before dinner. Not only will you increase your metabolism, but mustard seeds are a good source of antioxidants and omega-3s!"

Lisa Hubbard: Try New Recipes

Who said healthy eating has to be boring or bland? Lisa Hubbard, star of the “Element: Total Body Pilates with Mini Ball” kit, recommends firing up your creative juices in the kitchen by investing in a new cookbook and trying new healthy recipes!